Allow file:// based Uri's to be used in HttpClient when the BaseAddre…

…ss is set

Fixes https://devdiv.visualstudio.com/DefaultCollection/DevDiv/_workitems/edit/967582

Bumps the HttpClient part in mono/corefx at: mono/corefx@ee3acec

The test that would have caught this failure was disabled previously via:
mono@2f41175

mcs/class/System.Net.Http/HttpRequestMessage.Mono.cs

@@ -12,6 +12,10 @@ static bool IsAllowedAbsoluteUri (Uri uri)
 				return true;
 #endif
 
+			// Mono URI handling which does not distinguish between file and url absolute paths without scheme
+			if (uri.Scheme == Uri.UriSchemeFile && uri.OriginalString.StartsWith ("/", StringComparison.Ordinal))
+				return true;
+
 			return HttpUtilities.IsHttpUri (uri);
 		}
 	}

mcs/class/System.Net.Http/Test/System.Net.Http/HttpClientTest.cs

@@ -375,8 +375,7 @@ public void Send ()
 			Assert.AreEqual (response, client.SendAsync (request).Result, "#1");
 		}
 
-		[Test]
-		[Category ("NotWorking")]
+		[Test]		
 		public void Send_BaseAddress ()
 		{
 			var mh = new HttpMessageHandlerMock ();